Concerta is just ritalin in a patented time release form. The fast acting short lasting med that the doctor is referring to is probably going to be ritalin as well, so you are not actually "mixing different types of meds", you are just giving the same med, one in a time release, one in an immediate release form.
I believe fish oils help my son's mood issues and I give them as well, but we do have a prescription for 10mg immediate release ritalin to be used when Chase needs to focus later in the evening for a larger than usual amount of homework. He takes Ritalin LA, and usually that is sufficient, but there are times when he doesn't get to his homework until it has worn off, and he cannot focus enough to get through it when the med is not in his system.
If you have been following my recent posts, you know that we want to adjust my 11 year old son’s meds. He’s currently on 54mg Concerta, and it doesn’t seem to be helping his concentration level in school at all. And the past few weeks his appetite has decreased, he has had stomach aches, and is not sleeping at night. I did a two day trial off the meds one weekend, and all the problems went away. When I put him back on the meds, they all came back.